#include <iostream>
#include <cstdlib>
#include <iomanip>
#include <chrono>
#include <random>
#include <functional>
using namespace std;

int main ()
{
	unsigned seed = chrono::system_clock::now().time_since_epoch().count();
	default_random_engine engine {seed};
	uniform_int_distribution<int> distribution {0, 999};
	auto r {bind(distribution, engine)};  //needed for RNG
	
	const size_t quantity {750};

	int a[quantity];  //create the array

	for (int i {0}; i < quantity; ++i) {  //populate the array
		a[i] = r();
	}

	const size_t n {size(a)};

	cout << "I have generated " << quantity << " random numbers between 0 and 1000.\n";
	cout << "I will now generate a random target from those numbers to search for.\n";

	const int target = a[r() % quantity];  //randomly select a generated number to search for

	cout << "Let's find " << target << " in the following array:\n\n"; 	

	for (int i {0}; i < n; ++i) { 
		cout << setw(3) << a[i] << ", ";
		if (i % 15 == 14) {
			cout << "\n";
		}
	}

	cout << "\nFirst, we need to sort the random numbers from low to high.\n\n";

	for (int i {n}; i > 0;  --i) {   //bubble sort to get the array sorted lowest to highest
		for (int j = 0; j < i; ++j) {
			if (a[j] > a[j + 1]) {
				const int temp {a[j]};
				a[j] = a[j + 1];
				a[j + 1] = temp;
			}
		}
	}
	
	for (int i {0}; i < n; ++i) { 
		cout << setw(3) << a[i] << ", ";
		if (i % 15 == 14) {
			cout << "\n";
		}
	}

	cout << "\nNow that the array is organized from lowest to highest, we can use a binary search function to find "	<< target << ".\n";

	int low {0};
	int high {n};

	while (low <= high) {   //run the binary sort function, outputting the remaining possible options for the target number
		const int mid {(low + high) / 2};
		if (a[mid] == target) {
			cout << "\nWe found " << target << "!!\n\n";
			return EXIT_SUCCESS;
		} else if (a[mid] < target) {
			cout << "\nOur guess of " << a[mid] << " is too low.\nOur remaining options are:\n";
			low = mid + 1;
			for (int i = low; i <= high; ++i) {
				cout << setw(3) << a[i] << ", ";
			}
		} else {
			cout << "\nOur guess of " << a[mid] << " is too high.\nOur remaining options are:\n";
			high = mid - 1;
			for (int i = low; i <= high; ++i) {
				cout << setw(3) << a[i] << ", ";
			}
		}
	}
	cout << "Unfortunately, the target number could not be found.\n";
	return EXIT_FAILURE;
}